Electrical ignition assembly for liquid fuel burners



Jan. 3, 1961 4 J. L. BREESE ETAL 2,966,941

ELECTRICAL IGNITION ASSEMBLY FOR LIQUID FUEL BURNERS 1 Original FiledNov. 4, 1955 3 Sheets-Sheet 1 3 3.- a o o o 0 I0 2/ a 0 o o o V m I I s//V VE N 70195 JAMES L. BREESE. DECEASED c ARD F. VANTUBERGEN BJYASESHL.BREESEJII, EXECUTO'RS.

MILTON D. HUSTON Jan. 3, 1961 J. L. BREESE ET AL 2,966,941

ELECTRICAL IGNITION ASSEMBLY FOR LIQUID FUEL BURNERS Original Filed Nov.4, 1955 3 Sheets-Sheet 2 wvavrores JAMES .L. BREESE DECEASED, BY RICHARDF. VANTUBERGEN 8| MILTON D. HUSTON yj a rier C'arler Jttorneys JAMES L.BREESE,]I[, EXECUTORS.

Jan. 3, 1961 J. L. BREESE ETAL 2,966,941

ELECTRICAL IGNITION ASSEMBLY FOR LIQUID FUEL BURNERS Originalv FiledNov. 4, 1955 3 Sheets-Sheet 3 IA/ VE/V TORS JAMES L. BREESE, DECEASED,BY RICHARD F. VAN TUBERGEN a JAMES L. BREESEJII, EXECUTORS.

MILTON D. HUSTON ayj arfi'er Car'zer I Jttorn eys United States PatentCELECTRICAL IGNITION ASSEMBLY FORLIQUID FUEL BURNERS 'James'L. Breese,deceased, late of Santa Fe, N. Mex.,by :Richard F. Van Tubergen andJames L. Breese III executors, Santa Fe, N. Mex., and Milton D. Huston,Santa Fe, N. Mex., assignors to Controls Company of America, SchillerPark, lll., a corporation of Delaware Original application Nov. 4, 1955,'Ser. No. 544,918. ,Divgded and vthis application Feb. 25,-196 0, Ser.No.

3 Claims. (Cl. 158-91) This invention is directed to a new and improvedmethodand mechanismfor igniting the fuel in oil burners, and is adivision of co-pending application Serial ,No. 544,- 918, filed November4, 1955.

Qne purpose of the present inventionis to provide an improved method ofignition for oil burner pots wherein the possibility of explosionsduring the ignition period is materially lessened.

Another purpose is to provide a heat storage means for initiallyvaporizing a substantial volume of liquid hydrocarbon fuel at thestartingstage.

Yet another object is to provide means for bringing an oil. burner to ahigh fire condition with a minimum time lag after ignition.

Another purpose is an improved electrical ignitionas- .seinbly for oilburners wherein a flame spreads rapidly and evenly throughout the potupon ignition.

Another purpose is an improved supporting arrangement of a burner potand electrical ignition assembly.

Other objects will appear from time to time in the course of the ensuingspecification and claims.

Referring generally now to the drawings:

Figure l is an assembly view in section illustrating our improvedignition assembly in its supported position in a burner pot;

Figure 2 is a sectional view of the ignition assembly illustrated inFigure 1;

Figure 3 is an end elevation of the ignition assembly shown in Figure 2;

:Figure 4 is a sectional view looking in the direction of the arrowsshown at 4--4 in Figure 2;

Figure 5 is a sectional view of amodified form of the invention;

Figure 6 is an enlarged detailview of one element utilized in theassembly shown in Figure 5;

Figure 7 is an end view of the element illustrated in Figure 6;

Figure 8 is a sectional view of a further modification;

Figure 9 is an end view of the device illustrated in Figure 8; and

Figure 10 is a sectional illustrationof another modification.

Like elements are designated by likecharacters throughout thespecification and drawings.

Referring specifically now to the drawings and in the first instance toFigure 1;

We illustrate a heater casingl havingthe customary burner pot 2supported therein. The burner pot 2;has the customary apertures 3 whichare arrangedin a plurality of horizontal rows for the purpose ofadmitting primary and secondary air to the interiorof the burner pot.The space between the-casing and the pot is the high pressure side andthe area inside of and adjacent the pot wall isthe low pressure side.The bottom of the {pot-4 is adapted to receive a supply of oil for,burning ,lutions of the spiral.

7 ing extends.

within the pot. The fuel may be supplied by any suitable inletrepresented diagrammatically at 5. We wish it to be understood that thedetails of the heater casing and burner pot may be widely varied and theshowing .ofthe casing and burner pot in Figure 1 should betaken in adiagrammatic sense.

The bottomof the pot may include a sump 4a adjacent the fuel inlet so asto create some puddling of fuel adjacent to the inlet 5.

An electrical ignition assembly, designated generally at 6, includes agenerally cylindrical housing '7 which extends through the wall of theheater casing and thewall of the burner pot and terminates as at Satadjacent the bottom of. the pot and over the sump 4a. The ignitionassembly 6 may contact the sump do. As will be clear inFigure 1, thehousing 7 extends into the pot at an angle inclined to the horizontaland vertical. The assembly includes a circumferential shield 8 whichfits over the upper end of the housing exteriorly of the heater casing.Represented at 9 and 10 are a pair of electrical leads which may beconnected to any suitable source of electrical energy.

The housing 7 is preferably formed of metal so as to store heat therein.

According to the invention we provide means it r conducting fuel vaporfrom the bottom of the pot to the interior of the housing 7. A wickelement 11 is formed on the lower end of the housing. It preferablytakes the form of a spirally wound stainless steel strip which providesa plurality of passages 12 between the convo- The convolutlons cf thespiral surround and define a central aperture 13 which is generallycoaxial with the axis of the housing 7t it should be noted that inFigure 2 the convolutions of the spiral are offset from one another sothat the wick element has a plurality of the passages 12 extending to apoint closely adjacent to the pot bottom as will be seen most clearly inFigure 1.

A pair of spaced electrically conductive poles 14 and 15 are positionedwithin the housing 7 and connected to the leads 9 and 10. The poles 14and 15 may be supported by any suitable insulating members 16 and 17which are snugly received within the housing 7. The poles 14 and 15terminate adjacent the wick element 11. Thevpoles 14 and 15 conductelectrical energy to a resistance heating element which takes the formof a coil '18. The resistance heating element may be formed of Nichromewire or other equivalent material. The heating element 18 is opposed tothe central opening or aperture 13 as is seen most clearly in Figures 3and 4.

The housing 6 makes a snug fit with the openings in the pot wall andheater casing through which the hous We find it particularlyadvantageous to position the housing 6 at an angle to the horizontalwherev by the lower end of the housing is positioned adjacent the 'fuelinlet and adjacent the bottom of the pot.

The housing or tube 6 may be made liquid tight with respect to the wallof the burner pot 2 by any suitable means (not shown). It should benoted in this connection that the upper end of the tube or housingterminates at a point above the lowermost level of air inlet apertures3. At the same time, the ignition tube can be made removable if desired,so that a rectilinear upward and outward pull will remove the tube.

Figures 5, 6 and 7 illustrate a modified form of the invention. InFigure 5, for example, the pot is designated at 2' and is provided withair inlet apertures 3". The heater casing is designated at 1'. In thisform of the invention an opening 30 is formed in the pot wall adjacentthe lower portion thereof and adjacent to the -inserted.

generally cylindrical sleeve has, at its lower end, an opening 33corresponding in size to the opening 30. A fuel inlet pipe 34 is formedintegrally with the support 32 and is disposed at an acute angle theretoas appears in Figure '6. The support 32 is adapted to be welded orotherwise affixed to the pot wall so that the axis of the support isinclined to the pot wall and to the bottom of the pot. The

upper end of the support 32 is provided with an opening 35 through whichan ignitor tube assembly, similar in all respects to that illustrated inFigure 2, is removably In this form of the invention, the shield 36surrounds the upper end of the support 32.

It should be noted that the opening in the upper end of the support ispositioned at least as high as the lowermost level of air inletapertures in the pot Wall, which we have designated at 3a.

The heater casing is formed with an opening 37 allowing passage of thesupport 32 therethrough. The heater casing may be also provided with afitting 38 which has a diameter such as to snugly receive the shield 36.

In the form of the invention illustrated in Figure 8, the ignitor tubeis designated at 40 and includes a shield 41 which is adapted tosurround a support 42 which, for purposes of description, may be takento be of the same form as the support 32 illustrated in Figures 5, 6 and7. The shield 41 is spaced from the support 42 by indentations in thebody of the shield, thus providing a space for the passage of air to theinterior of the support. Electrically conductive poles 43 and 44 arefixed to the end Wall of the shield 41 and extend through the tube orhousing 49. A resistance heating element 45 is fixed to the polesadjacent the inner or lower end of the tube 40. Electrical leads may beconnected to the ends of the poles adjacent the shield 41. In this formof the invention a metallic wick is formed of several super-imposedlayers of stainless steel screen wire. The wick is designated at 46. Itshould be noted that the wick 46 surrounds the heating element 45 and issupported at the lower end of the tube 40. The upper end of the tube isprovided with air inlet apertures 47 so that air may pass to theinterior of the tube. The shield 41 is spaced from the support 42 sothat a flow of air following the path of the arrows shown in Figure 8may pass from the exterior of the burner pot to the interior of thetube.

The wick element 46 defines what is in effect, a combustion chamber atthe lower end portion of the tube 40, and primary air for combustionpasses to this combustion chamber from the apertures 47 while secondaryair passes through the space between the support 42 and tube 40.

In Figure the burner pot is designated at 50 and is provided with rowsor levels of air inlet apertures 51. In this form of the invention asupport 52 is joined to the pot wall and is inclined to the wall of thepot as well as the bottom of the pot in a manner similar to the support32 in Figure 5. An ignitor tube 53 is removably inserted in the support52. The ignitor tube is provided with a shield 54 at its upper endportion. Electrically conductive poles 55 and 56 with terminals at theirouter ends extend through the shield and terminate adjacent the lowerend of the tube. A resistance heating element 57 is connected to thesetwo poles at their lower ends. A metallic wick of the form describedwith reference to Figure 8 is supported at the lower end of the tube asat 58. The wick 58 is positioned closely adjacent the sump 58a in thebottom wall of the burner pot. The sump 58a is important as it permitsthe pooling of a fair supply of oil to facilitate rapid vaporization forquickly bringing the burner to full fire.

The tube 53 stores up heat radiated from the ignitor elements andfacilitates the vaporization of the oil drawn up by the wick 58. If thetube 53 is too close to the ignitor elements, the vapor becomes more ofa fog and is not a combustible mixture, and, hence, is unsatisfactory.If, on

and the ignitor tube 53 is increased appreciably, the

A fuel inlet is designated at 60'.

current requirements go up and the life of the ignitor elements isshortened. Preferably the clearance between the ignitor tube 53 and theignitor elements is just sufficient to produce a combustible mixture asopposed to an incombustible fog.

The shield 54 is provided with indentations 59 that make a snug fit withthe exterior of the support 53. An end plate 59a is joined to the tube53 and overlies the upper end of tube 53. End plate 59a is spaced fromthe shield 54 as by indentations 59b. Apertures 59c are formed in theend plate so as to allow primary air for combustion to fiow through thespaces between indentations 59, thence through the spaces betweenindentations 59b and down to the area adjacent heating element 57. Theflow is indicated by the arrows in Figure 10. It supplies fuel through aspray nozzle 60 which is located at approximately the mid-point of thesupport 52. Oil sprayed through the nozzle 60 may pass downwardlythrough the space between the support 52 and tube 53.

Whereas we have shown and described an operative form of our invention,we wish it to be understood that there are many modifications of thisinvention which will fall within the scope and spirit of the inventionand which will be apparent to those skilled in the art. The drawings anddescription of the invention should be taken in a diagrammatic orillustrative sense and the scope of the invention should be limited onlyby the scope of the hereinafter appended claims.

The use and operation of our invention is as follows:

In each form of the invention we position an ignitor tube or housing atan angle to the horizontal. This angle is on the order of 45. Thisparticular disposition of the ignitor tube facilitates the location ofthe electrical leads at a point remote from the pot thus avoiding damageto the leads due to the heat in the pot. In each form of the invention,the upper end of the support or housing for the electrically conductivepoles terminates at a level above the lowermost level of air inletapertures in the pot. Thus if any flooding of the pot occurs fuel willspill out through the primary air apertures rather than through theignition tube. In each form of the invention a metallic wick providescapillary passages for fuel vapors at a point adjacent the resistanceheating element and in each form of the invention these passagessurround an opening opposed to the heating element.

In each form of electrical ignition assembly the hydrocarbon fuel isinitially heated and gasified by electrical energy. When current issupplied to the resistance heating element the metallic wick will beheated to a sufficient temperature in relation to the volume of fuelinvolved, so that when fuel begins to flow, and the wick fills withliquid fuel, the stored heat in the wick is itself sufficient tovaporize at least the initial increment of fuel to the wick. This vaporforms about the resistance heating element, and also, in the spaceimmediately exterior to the Wick. In effect, the wick and the adjacentportions of its support members including the housing and wick supporttube form a reservoir.

In each form of the invention means are provided for circulating airthrough the area of the combustion chamber adjacent the heating element.In Figure 2, for example, air may circulate through the openings 12 and13. In the forms of the invention illustrated in Figures 8 through 10inclusive, air external to the burner pot is supplied through theignition tube to the combustion chamber surrounding the heatingelements. Secondary air is supplied to the area surrounding the wick.This flow of air in all cases is insufiicient to cool the heatingelement, when energized, below the ignition temperature of the fuel. Theflow of air is sufiicient, however, to initiate primary combustion.

As the vapor due to the stored heat in the wick forms,

or almost immediately after it begins to form, the vapor in the housingwithin the tube and inside of the wick is ignited by the resistance andexplodes out through the housing. This initial flame is directeddownwardly toward the bottom of the pot and at a point relatively closeto the pot side wall. At the same time, or instantaneously thereafter,the vapor in the space exterior to the wick is ignited and the endresults is a substantial combustion of vaporized fuel which is efiectiveto initiate further vaporization and consequent combustion, the ignitionof the pot being thus started. Thus the flame will spread rapidly andevenly over the surface of oil covering the pot bottom.

In each form of the invention this ignition tube is simply insertedthrough the pot wall and may be removed for inspection and repair ifnecessary. The ignition tube may be removed by a simple rectilinearupward and outward pull. In Figures 5 through 10, the upper opening inthe support is well above the lowermost row of air inlet apertures andfuel spillage due to flooding of the pot will occur through thelowermost row of apertures rather than through the support.

What is claimed is:

1. In a vaporizing type oil burner, the combination comprising a burnerbody having a floor and upstanding walls extending therefrom and whereinoil is adapted to be supplied to at least a portion of the floor of theburner body, an electric ignition element positioned within said bodyand vertically spaced from the floor, a hood surrounding a portion ofsaid element and defining a chamber around said portion, said hoodhaving a wall portion between said element and said floor, said wallportion being spaced from said portion of said floor, said hood havingan opening in a lower portion thereof, and a wick extending from atleast immediately adjacent the portion of the floor of said burner bodythrough said opening, said wick being out of contact with said elementand terminating within said chamber, said opening in said lower portionof said hood being located in a position such that the portion of saidwick adjacent said opening is subjected to radiant heat from saidelement, whereby oil is metered from said portion of said floor to saidchamber by said wick and radiant heat from said element vaporizes aportion of the oil in said wick, the amount of oil which is vaporizeddepending on the degree of energization of said element and the size ofsaid opening of said hood.

2. The structure of claim 1 characterized by and including means fordelivering air through the interior of said hood and toward said wick.

3. The structure of claim 1 further characterized by means for poolingoil in said floor portion of the burner body adjacent said wick.

References Cited in the file of this patent UNITED STATES PATENTS2,553,975 Little May 22, 1951 2,712,352 Manor et a1. July 5, 19552,779,398 Brown Ian. 29, 1957

